The present disclosure relates to wellbore operations, and more particularly, using dynamic underbalancing by non-explosive means to increase fluid flow within a wellbore.
After drilling the various sections of a subterranean wellbore that traverses a hydrocarbon-bearing formation, a well operator may undertake perforation operations to increase productivity in one or more sections of the wellbore. However, this increased productivity may slow over a period of time due to the perforation channels being obstructed, for example, by sand, wax, scale, and other debris. The period of time and the degree of reduced productivity may vary depending on factors such as the formation type, type of oil being produced from the formation, and the type of perforation job initially performed.
There are currently many ways to treat a well in attempting to counteract perforation channel obstructions and thereby increase productivity from the formation. For instance, a well may be acidized, additional fracturing may be performed, or the area may be re-perforated. With a re-perforation job in particular, some techniques implement explosives combined with dynamic underbalancing in attempting to clear the debris out of the perforation channels. The dynamic underbalancing technique generates a pressure differential, wherein the pressure within the wellbore is significantly lower than the pressure in the formation outside the wellbore. Thus, upon detonating one or more explosives adjacent the wellbore, a rapid decompression occurs and debris within perforation channels defined in the formation is drawn back through the wellbore walls and into the annulus or work string, thereby cleaning out the perforation channels.
This process, however, is inherently dangerous due to the need to use explosives. Beyond danger to human lives, the use of explosives creates a storage problem around the rig site. Moreover, the process is limited in efficiency due to single use operations of the explosives. Also, the size of the explosives required oftentimes presents a problem; too many explosives may damage the well, and not enough explosives may not adequately complete the job needed. Workarounds may include requiring additional perforation guns, explosives, or downhole deployment and retrieval of such tools.